Foods or drinks frequently contain various bitter substances which, although they are characteristic (for example, caffeine in tea or coffee), they can also greatly decrease the value (for example limonoids in citrus juices, bitter aftertaste of many synthetic sweeteners such as aspartame or saccharin). To lower the natural content of bitter substances, therefore, frequently subsequent treatment is necessary, for example by extraction as in the decaffeination of tea or coffee, or enzymatically, for example treatment of orange juice with a glycosidase to destroy the bitter naringin, or use of special peptidases in the ripening of cheese. This treatment causes stress to the product, produces wastes and also produces, for example, solvent residues and other residues (enzymes) in the products. It is, therefore, desirable to find substances, preferably natural or nature-identical substances, which can effectively suppress, or at least decrease, the bitter taste or aftertaste.
Suppressing the bitter taste in many pharmaceutically active compounds is particularly important, since, as a result, the readiness of the patients, in particular in the case of patients who are sensitive to bitter taste, such as children, to take the preparation orally, can be significantly increased. Many pharmaceutically active compounds, for example quinine, have a pronounced bitter taste and/or aftertaste.
To date, only a few substances have been described which suppress bitterness and have no inherent taste. Thus, U.S. Pat. No. 6,083,459 describes bitter-masking amino acid derivatives which do not, however, occur in nature. 2(-4-Methoxyphenoxy)propionic acid sodium salt (Lactisol) exhibits a weak bitter-reducing effect at relatively high concentrations (450 ppm), as reported in Chem. Senses, 1994, vol. 19, pp. 349 ff.; however, it is a problem that the substance at the same time suppresses the sweet taste impression (U.S. Pat. No. 4,567,053). Neohesperidin dihydrochalcone also exhibits a bitter-reducing effect, but is primarily a sweetener (see Manufacturing Chemist 2000, July issue, pp. 16-17), which also has a disturbing action in non-sweet applications. Although U.S. Pat. No. 5,580,545 describes taste-modifying properties for some flavones (2-phenylchrom-2-en-4-ones), a bitter-reducing or bitter-suppressing action was not found.
Sodium chloride exhibits a bitter-masking effect against many bitter substances (e.g. Nature, 1997, vol. 387, p. 563); however, the intake of relatively large amounts of salt can lead, for example, to cardiovascular disorders.
Concentrated extracts of Herba Santa or simple aqueous or alcoholic extracts of the same exhibit a weak bitter-masking action towards quinine; however, to date the individual constituents have not been analyzed for their activity; in addition, the extracts display a rather strong herb-like inherent taste.
WO 00/21,390 describes polyglutamic acid as a bitterness-suppressing agent; relatively high concentrations in the region of 1% by weight are required. A lipoprotein consisting of β-lactoglobulin and phosphatic acid also exhibits a bitter-masking effect (EP-A 635 218). Such polymers, however, are difficult to characterize and to standardize.
The flavone glycoside Neodiosmin (5,7-dihydroxy-2-(4-methoxy-3-hydroxyphenyl)-7-O-neohesperidosyl-chrom-2-en-4-one) shows a bitter-suppressing action (U.S. Pat. No. 4,154,862), but features a disaccharide radical which makes preparation and applicability of the substance difficult.